June 2014 – EES Blog

Archive for June, 2014

Solar cells: Tiny balls of fire – EES article featured in The Economist

30 Jun 2014

A recent article in EES on how to increase the light-absorbing capability of a photoelectrochemical cell by arranging spheres of tungsten oxide has been selected as one of the three science articles featured in this week’s issue of The Economist. The article is written by Florent Boudoire and co-workers at the Swiss Federal Laboratories for Materials Science and Technology, where the group’s research efforts are concentrated on high performance ceramic materials for energy and the environment.

The Economist offers authoritative insight and opinion on international news, politics, business, finance, science, technology and the connections between them.

Read the full article on the website now!

Also check out the original research article which has been made free to access for a limited period of time! –

Florent Boudoire et al., Energy Environ. Sci., 2014, DOI: 10.1039/C4EE00380B

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Organic solar cells reach manufacturing milestone

27 Jun 2014

In an impressive feat of engineering, scientists in Denmark have devised a rapid, scalable and industrially viable way to manufacture large sheets of flexible organic tandem solar cells. Their successful application of roll-to-roll processing is a significant achievement for this emerging renewable technology. Organic solar cells reach manufacturing milestone

An organic photovoltaic (OPV) solar cell is a polymer-based thin film solar cell. OPV solar cells have been the focus of much research as they are lightweight, flexible, inexpensive, highly tuneable and potentially disposable. They are also unparalleled in the number of times that they can pay back the energy used in their manufacture.

In the quest to improve the efficiency of OPVs, which, in addition to operational lifetime, is currently their key limitation, various new materials, processing methods and device architectures have been investigated. Among these is the tandem cell, where multiple junctions are stacked upon one another. This can increase the efficiency of the cell by not only increasing the number of junctions, but, along with careful selection of complimentary materials, can make it possible to harvest photons from a broader region of the spectrum. However, this more complicated architecture renders their manufacture significantly more challenging.

Interested to find out more? Read the full article by William Bergius in Chemistry World.

Read the original article in Energy and Environmental Science:

Scalable, ambient atmosphere roll-to-roll manufacture of encapsulated large area, flexible organic tandem solar cell modules
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01223B
Thomas R. Andersen, Henrik F. Dam, Markus Hösel, Martin Helgesen, Jon E. Carlé, Thue T. Larsen-Olsen, Suren A. Gevorgyan, Jens W. Andreasen, Jens Adams, Ning Li et al.

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Harvesting electricity from seawater

16 Jun 2014

A new type of blue energy harvesting device may offer a practical method of continuous coastal electricity generation.

In 2011, Stanford researchers described a new form of energy harvesting device coined as a “mixing entropy battery” in Nano Letters¹. Their device capitalized on the chemical energy available in a system where an ion concentration gradient is present; in this case where low salinity wastewater or river water was mixed with ~0.6 M NaCl rich seawater. It is estimated that during this mixing process, there is a free energy reduction of 2.2 kJ per liter of freshwater.

Extractable energy depends on charging time

Using two electrodes, one Na⁺ selective the other Cl^– selective, a charging state exists when the battery is exposed to low salinity water, where ions in the electrodes are removed via a concentration gradient. Next, sea water replaces the low salinity water and the potential between the electrodes increases. This is followed by a discharge state where ions from the higher concentration solution reincorporate into their ion selective electrode . This charge/discharge cycle produces extractable energy per cycle as described in the figure shown.

In the present work, the same group investigates replacing the cathode material with a higher capacity material, Na₄Mn₉O₁₈, as opposed to the previously reported Na₂M₅O₁₀. An overall improvement was observed when researchers simulated batteries hooked up in a series, by passing the same effluent wastewater 12 times through the same cell. In doing so, the cumulative energy produced was 0.44 kWh/m³of wastewater, compared to the theoretical maximum of 0.65 kWh/m³. This denotes an overall efficiency of 68%. Future considerations include reducing the number of batteries required in series, as well as eliminating the use of silver as a Cl^– selective electrode, for environmental concerns.

1.) Nano Lett., 2011, 11, 1810–1813

Interested? Read the full advance article in Energy and Environmental Science here:

Performance of a mixing entropy battery alternately flushed with wastewater effluent and seawater for recovery of salinity-gradient energy

Meng Ye, Mauro Pasta, Xing Xie, Yi Cui, and Craig S. Criddle
Energy Environ. Sci., 2014, Advance Article
DOI: 10.1039/C4EE01034E

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The future is lead-free for perovskite solar cells

05 Jun 2014

A lead-free and non-toxic alternative to current perovskite solar-cell technology has been reported by researchers in the UK: tin halide perovskite solar cells. They are also cheaper to manufacture than the silicon solar cells currently dominating the market. The future is lead-free for perovskite solar cells

Nakita Noel, part of Henry Snaith’s research team at the University of Oxford, describes how perovskite materials have caused a bit of a whirlwind since they came out in 2009: ‘Everybody that’s working in the solar community is looking to beat silicon.’ Despite the high efficiency of conventional crystalline silicon solar cells (around 20%), high production and installation costs decrease their economic feasibility and widespread use.

The challenge to find a cheaper alternative led to the development of perovskite-based solar cells, as organic–inorganic metal trihalide perovskites have both abundant and cheap starting materials. However, the presence of lead in some semiconductors could create toxicology issues in the future. As Noel puts it ‘every conference you present at somebody is bound to put up their hand and ask “What about the lead – isn’t this toxic?”

Interested to find out more? Read the full article by Vicki Marshall in Chemistry World.

Read the original article in Energy & Environmental Science.

Lead-Free Organic-Inorganic Tin Halide Perovskites for Photovoltaic Applications
Nakita K. Noel, Samuel D. Stranks, Antonio Abate, Christian Wehrenfennig, Simone Guarnera, Amir Haghighirad, Aditya Sadhanala, Giles E Eperon, Sandeep K. Pathak, Michael B Johnston, annamaria petrozza, Laura Herz and Henry Snaith
Energy Environ. Sci., 2014, Accepted Manuscript
DOI: 10.1039/C4EE01076K

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Designing next-generation activated carbons for advanced energy storage applications

05 Jun 2014

Activated carbons for energy storage

In this interesting and informative article, M. Sevilla and R. Mokaya review state-of-the-art synthesis methods for the preparation of activated carbons and their application in energy storage systems. Specifically, the authors detail recent developments in the control of properties such as pore size distribution, surface area and structural and chemical characteristics – and how such properties relate to performance in hydrogen storage and supercapacitors.

Activated carbons have a number of desirable features that make them attractive for use in advanced energy-storage systems. As well as being relatively light-weight, low-cost and chemically inert, they also have very large surface areas (> 1000 m²/g) and high micropore volumes in which to interact with other species. This makes activated carbons particularly useful as supercapacitor electrodes and hydrogen storage materials – where performance is strongly related to surface area and pore characteristics.

In this review, recent developments in the fabrication of activated carbons are discussed, focusing particularly on methods which allow the control of features, such as pore size distribution, surface area and physical and chemical characteristics such as texture, morphology and heteroatom-doping. The relationship between these properties and the performance of these materials as supercapacitor electrodes and their use in hydrogen storage is also looked at in detail, providing a guide for the direction of future research in this very active field.

Interested? Read the full article here:

Energy storage applications of activated carbons: supercapacitors and hydrogen storage

Marta Sevilla and Roberts Mokaya

Energy Environ. Sci., 2014, 7, 1250–1280

DOI: 10.1039/C3EE43525C

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EES Blog

Archive for June, 2014

Solar cells: Tiny balls of fire – EES article featured in The Economist

Organic solar cells reach manufacturing milestone

Harvesting electricity from seawater

The future is lead-free for perovskite solar cells

Designing next-generation activated carbons for advanced energy storage applications

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